40{33 {0 Microscope objective

ABSTRACT

A four member microscope objective having a numerical aperture of substantially 0.66 and a magnification of substantially 40 X provides a substantially flat image field of about 24mm.

United Dunes r atent m1 [111 3,902,791

Shoemaker Sept. 2, 1975 1 40x MICROSCOPE OBJECTIVE [75] Inventor: Arthur H. Shoemaker, East Aurora, Primary Exami"er P'aul Sacher Attorney, Agent, or Firm-Alan H. Spencer; William C. Nealon; H. R. Berkenstock, Jr. [73] Assignee: American Optical Corporation,

Southbridge, Mass.

[22] Filed: Apr. 26, 1974 [211 Appl. No.: 464,386 [571 ABSTRACT [52] U S Cl 350/175 Mb 350/176, 350/224 A four member microscope objective having a numer- [5 l] ulnt Ci 602;; 9/34. GOZB 1/00 ical aperture of substantially 0.66 and a magnification [58] Fieid 3 50 H7 5 M 224 176 of substantially 40X provides a substantially flat image field of about 24mm.

[56] References Cited UNITED STATES PATENTS 3 Claims, 1 Drawing Figure 3,380,793 4/1968 Klein 350/175 ML RIO 1 2 V I 40X MICROSCOPE OB C TABLE II Continued BACKGROUND OF THE INVENTION 1 Le I Mum Mk space The present invention relates to microscope objecm 5990 tives and more particularly to an achromatic micro- 5 v T,==3.500 scope objective having a numerical aperture of sub- RP-lzmo 660 stantially 0.66 and a magnification of substantially 40X, in which chromatic and spherical aberrations, coma, and astigmatism are well corrected while yet IV RF 7-416 1 providing a substantially flat image field of about 10 Rmzqfi'sm Trlooo 24mm when used with a telescope objective as described in US. Pat. No. 3,355,234.

The stated values of the ob ectives heremabove are DRAWING AND INVENTION variable within the limits of normal manufacturing tol- The drawing is an optical diagram of the microscope l5 erances', objective x having lens elements 1, 11, in and iv in optiwhat clalmed cal alignment along an axis extending from the object A microscope ObJeCUVe havmg a numerical ape!" plane 0 The fi t element 1 is a concavo convex Positure of substantially 0.66, which is well corrected for tive singlet, the second element II is a concavo-convex chromatic "P aberrations Spherical aberration, positive singlet, the third element III is a concavocoma Q aSIlgmatISm f four elements aligned along convex positive doublet and the fourth element IV is a optlcal axis extendmg fl P J Plane, concavo-convex negative doublet. The parameters of Pnses, a concavo'convex posltwfalsmglet 1 as the first objective x are set forth in Table I wherein the axial element, a concave-convex poslllve a g II as the thicknesses of successive lens elements are designated Second elFmenti a concavo'convex Posmve doubletnl T1 to T6, and the successive axial spaces from the obas the thud element and a concavo-convex negative ject plane (designated 0) are S1 to S4. The successive doublet Iv as the fourth element lens radii are designated R1 to R10 where the minus 2. The microscope objective of claim 1 having the sign applies to surfaces whose center of curvature following optical parameters: lies on the object side of their vertices. The refractive Rama Abbe indices and Abbe numbers of the glasses in the 'succes- Lens Radius Thickness Space tiv Index Number sive lenses are absolute fixed values designated ND( 1) s 5778: to ND(6), and 11(1) to 11(6) respectively, and F is the RI 052926]; objective focal length in millimeters. T,=0.87336F ND( =|.78s33 v(l)=50.47

TABLE I Refractive Abbe Lens Radius Thickness Space Index Number S,=().l5778F R, 0.52926F l i T,=0.87336F ND( 1 )=l.78833 V( 1 )=50.47

s,==0.o54591= R, 7.87] l6F 11 T2=0.43668F ND(2)=l.78833 v(2)=50.47

s,,=0.021s3F R, =17.4o323i= T ,=0.3275lF ND(3)=l.8049l v(3)=25.42 lll R, l.30786F T.,=0.764l9F ND(4)=l.7l687 v(4)=47.98 2.70087F s,=1.x90s2|= R, 12.83970F T,,=0.32751F ND(5)=l.80784 v(5)=40.74 1v R,,= l.6l92lF T,,=0.o55021= ND(6)--l.54804 v(6)=45.75 R,,,= 3.60479F A specific embodiment of the present invention is an R2 0-84825 F 8 =0 05459: objective with a focal length of 4.580mm and has the 187116.: 2 values Set forth m Table II T=Q43668F ND(2)=I.78833 u(2)=50.47

R, 1.46441F TABLE II s ,=0.o21s31= R =-17.40323F Rad'us Th'ckmss Space s T,,=0.3275lF ND(3)=l.8049l i/(3)=2s.42

R 2 424 111 RG= 1.30786F I T =4 000 T,=0.7o4191= ND(4)=l.7l687 owns R? 3 885 R,=- 2.70087F 50:0 2500 s,=l.s90s2F R? 050 R, =l2.83970F I Flow T ,=0.32751F ND(5)-=l.80784 v(5)=40.74

r= 6707 IV R,= l.6l92lF SFQWUO T,,=0.65502F ND(6FL54804 v(6)=45.75 R,.,=-79.707

the successive lenses are ND(1) to ND(6), v( 1) to 1 (6) respectively and F is the objective focal length in millimeters.

3. The microscope objective of claim 1 wherein F is of the vertices, refractive indices and Abbe numbers of 4.580. 

1. A microscope objective having a numerical aperture of substantially 0.66, which is well corrected for chromatic image aberrations, spherical aberration, coma and astigmatism and four elements aligned along an optical axis extending from an object plane, comprises, a concavo-convex positive singlet I as the first element, a concavo-convex positive singlet II as the second element, a concavo-convex positive doublet III as the third element and a concavo-convex negative doublet IV as the fourth element.
 2. The microscope objective of claim 1 having the following optical parameters:
 3. The microscope objective of claim 1 wherein F is 4.580. 